Merged pipeline hygiene

- Lazy shore-band noise, zero interpolator groups dropped, inline prefill, dead streams removed

core/src/main/java/art/arcane/iris/generation/context/ChunkContext.java

@@ -17,8 +17,6 @@ import art.arcane.volmlib.nativelib.terrain.NativeBiome;
 import art.arcane.volmlib.util.hunk.Hunk;
 import art.arcane.iris.generation.concurrent.MultiBurst;
 
-import java.util.ArrayList;
-import java.util.List;
 import java.util.concurrent.CompletableFuture;
 
 public class ChunkContext {
@@ -95,38 +93,11 @@ public class ChunkContext {
             if (hydrologyRuntime != null && (resolvedPlan.height || resolvedPlan.biome)) {
                 hydrologyRuntime.prepareChunkColumns(x, z);
             }
-            List<Runnable> fillTasks = new ArrayList<>(6);
+            if (shouldPrefillAsync(resolvedPlan, complex.isPlatformMainThread())) {
-            if (resolvedPlan.height) {
+                prefillAsync(resolvedPlan);
-                fillTasks.add(() -> height.fillRounded(roundedHeight));
-            }
-            if (resolvedPlan.biome) {
-                fillTasks.add(new PrefillFillTask(biome));
-            }
-            if (resolvedPlan.rock) {
-                fillTasks.add(new PrefillFillTask(rock));
-            }
-            if (resolvedPlan.fluid) {
-                fillTasks.add(new PrefillFillTask(fluid));
-            }
-            if (resolvedPlan.region) {
-                fillTasks.add(new PrefillFillTask(region));
-            }
-            if (resolvedPlan.cave) {
-                fillTasks.add(new PrefillFillTask(cave));
-            }
-
-            if (!shouldPrefillAsync(resolvedPlan, fillTasks.size())) {
-                for (Runnable fillTask : fillTasks) {
-                    fillTask.run();
-                }
             } else {
-                List<CompletableFuture<Void>> futures = new ArrayList<>(fillTasks.size());
+                prefillSurface(resolvedPlan);
-                for (Runnable fillTask : fillTasks) {
+                prefillPalettes(resolvedPlan);
-                    futures.add(CompletableFuture.runAsync(fillTask, MultiBurst.burst));
-                }
-                for (CompletableFuture<Void> future : futures) {
-                    future.join();
-                }
             }
             if (capturePrefillMetric) {
                 metrics.getContextPrefill().put((System.nanoTime() - totalStartNanos) / 1_000_000D);
@@ -134,14 +105,46 @@ public class ChunkContext {
         }
     }
 
-    static boolean shouldPrefillAsync(PrefillPlan prefillPlan, int fillTaskCount) {
+    static boolean shouldPrefillAsync(PrefillPlan prefillPlan, boolean platformMainThread) {
-        if (prefillPlan == PrefillPlan.NATURAL_TERRAIN || fillTaskCount <= 1 || !IrisPlatforms.isBound()) {
+        if (!platformMainThread || prefillPlan == PrefillPlan.NATURAL_TERRAIN || prefillPlan == PrefillPlan.NONE
+                || !IrisPlatforms.isBound()) {
             return false;
         }
 
         return !MultiBurst.burst.ownsCurrentThread();
     }
 
+    private void prefillSurface(PrefillPlan prefillPlan) {
+        if (prefillPlan.height) {
+            height.fillRounded(roundedHeight);
+        }
+        if (prefillPlan.biome) {
+            biome.fill();
+        }
+    }
+
+    private void prefillPalettes(PrefillPlan prefillPlan) {
+        if (prefillPlan.rock) {
+            rock.fill();
+        }
+        if (prefillPlan.fluid) {
+            fluid.fill();
+        }
+        if (prefillPlan.region) {
+            region.fill();
+        }
+        if (prefillPlan.cave) {
+            cave.fill();
+        }
+    }
+
+    private void prefillAsync(PrefillPlan prefillPlan) {
+        CompletableFuture<Void> surface = CompletableFuture.runAsync(() -> prefillSurface(prefillPlan), MultiBurst.burst);
+        CompletableFuture<Void> palettes = CompletableFuture.runAsync(() -> prefillPalettes(prefillPlan), MultiBurst.burst);
+        surface.join();
+        palettes.join();
+    }
+
     public void setTerrainBiomeOutput(Hunk<NativeBiome> terrainBiomes) {
         this.terrainBiomes = terrainBiomes;
     }
@@ -295,17 +298,4 @@ public class ChunkContext {
 
     public record TransitionTerrainColumn(Terrain3DColumn solids, int fluidHeight) {
     }
-
-    private static final class PrefillFillTask implements Runnable {
-        private final ChunkedDataCache<?> dataCache;
-
-        private PrefillFillTask(ChunkedDataCache<?> dataCache) {
-            this.dataCache = dataCache;
-        }
-
-        @Override
-        public void run() {
-            dataCache.fill();
-        }
-    }
 }

core/src/main/java/art/arcane/iris/generation/runtime/Engine.java

@@ -77,7 +77,6 @@ import java.awt.Color;
 import java.nio.file.Path;
 import java.util.Locale;
 import java.util.Set;
-import java.util.UUID;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicLong;
@@ -224,10 +223,6 @@ public interface Engine extends DataProvider, Fallible, BlockUpdater, Renderer,
 
     EngineWorldManager getWorldManager();
 
-    default UUID getBiomeID(int x, int z) {
-        return getComplex().getBaseBiomeIDStream().get(x, z);
-    }
-
     int getParallelism();
 
     void setParallelism(int parallelism);

core/src/main/java/art/arcane/iris/generation/runtime/IrisComplex.java

@@ -29,7 +29,6 @@ import art.arcane.iris.generation.subterrain.SubterrainRasterizer;
 import art.arcane.iris.configuration.IrisSettings;
 import art.arcane.iris.pack.loading.IrisData;
 import art.arcane.iris.pack.loading.IrisRegistrant;
-import art.arcane.iris.generation.cache.Cache;
 import art.arcane.iris.studio.generation.BiomeBuffetLayout;
 import art.arcane.iris.world.history.GenerationBlend;
 import art.arcane.iris.world.history.TransitionGenerationPlan;
@@ -52,8 +51,6 @@ import art.arcane.iris.generation.terrain.InferredType;
 import art.arcane.iris.generation.biome.IrisBiome;
 import art.arcane.iris.generation.biome.IrisBiomeGeneratorLink;
 import art.arcane.iris.pack.value.IrisRaritySelection;
-import art.arcane.iris.generation.decoration.IrisDecorationPart;
-import art.arcane.iris.generation.decoration.IrisDecorator;
 import art.arcane.iris.generation.noise.IrisGenerator;
 import art.arcane.iris.generation.noise.IrisGeneratorStyle;
 import art.arcane.iris.generation.terrain.ContinentGenerator;
@@ -80,12 +77,12 @@ import art.arcane.iris.generation.terrain.ProceduralTerrainHeightSampler;
 import art.arcane.iris.generation.terrain.HydrologyBankTerrainRuntime;
 import art.arcane.iris.spi.IrisPlatforms;
 import art.arcane.iris.spi.IrisLogging;
-import art.arcane.volmlib.nativelib.terrain.NativeBiome;
 import art.arcane.volmlib.nativelib.terrain.NativeBlockState;
 import art.arcane.volmlib.util.collection.KList;
 import art.arcane.iris.generation.block.DataProvider;
 import art.arcane.volmlib.util.math.M;
 import art.arcane.volmlib.util.math.RNG;
+import art.arcane.volmlib.util.interpolation.IrisInterpolation;
 import art.arcane.volmlib.util.interpolation.NoiseBounds;
 import art.arcane.volmlib.util.interpolation.NoiseBoundsProvider;
 import art.arcane.volmlib.util.noise.CNG;
@@ -99,8 +96,10 @@ import lombok.Setter;
 import lombok.ToString;
 
 import java.lang.ref.WeakReference;
+import java.util.ArrayDeque;
 import java.util.Arrays;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.EnumMap;
@@ -133,6 +132,8 @@ public class IrisComplex implements DataProvider {
     private static final double SLOPE_RUN = 3D;
     /** A sheer coast would let shoreMinimumWidth buy unbounded height, so the shore band stops climbing here. */
     private static final double MAX_SHORE_BAND_GRADIENT = 3D;
+    static final double SHORE_NOISE_LOWEST = -0.5D;
+    static final double SHORE_NOISE_HIGHEST = 1.5D;
     private static final Comparator<IrisInterpolator> INTERPOLATOR_ORDER = Comparator
             .comparing((IrisInterpolator interpolator) -> interpolator.getFunction().name())
             .thenComparingDouble(IrisInterpolator::getHorizontalScale);
@@ -176,7 +177,6 @@ public class IrisComplex implements DataProvider {
     private ProceduralStream<IrisRegion> regionStream;
     private ProceduralStream<Double> regionStyleStream;
     private ProceduralStream<Double> regionIdentityStream;
-    private ProceduralStream<UUID> regionIDStream;
     private ProceduralStream<InferredType> bridgeStream;
     private ProceduralStream<IrisBiome> landBiomeStream;
     private ProceduralStream<IrisBiome> caveBiomeStream;
@@ -185,10 +185,8 @@ public class IrisComplex implements DataProvider {
     private ProceduralStream<IrisBiome> baseBiomeStream;
     @Getter(AccessLevel.NONE)
     private final transient boolean reuseNaturalBaseBiome;
-    private ProceduralStream<UUID> baseBiomeIDStream;
     private ProceduralStream<IrisBiome> naturalTrueBiomeStream;
     private ProceduralStream<IrisBiome> trueBiomeStream;
-    private ProceduralStream<NativeBiome> trueBiomeDerivativeStream;
     private ProceduralStream<Double> naturalHeightStream;
     private ProceduralStream<Double> baseTerrainHeightStream;
     @Getter(AccessLevel.NONE)
@@ -230,13 +228,6 @@ public class IrisComplex implements DataProvider {
     private ProceduralStream<Double> riverCarveWeightStream;
     private ProceduralStream<Double> riverWaterSurfaceStream;
     private ProceduralStream<Integer> topSurfaceStream;
-    private ProceduralStream<IrisDecorator> terrainSurfaceDecoration;
-    private ProceduralStream<IrisDecorator> terrainCeilingDecoration;
-    private ProceduralStream<IrisDecorator> terrainCaveSurfaceDecoration;
-    private ProceduralStream<IrisDecorator> terrainCaveCeilingDecoration;
-    private ProceduralStream<IrisDecorator> seaSurfaceDecoration;
-    private ProceduralStream<IrisDecorator> seaFloorDecoration;
-    private ProceduralStream<IrisDecorator> shoreSurfaceDecoration;
     private ProceduralStream<NativeBlockState> rockStream;
     private ProceduralStream<NativeBlockState> fluidStream;
     private Map<String, ProceduralStream<NativeBlockState>> hydrologyFluidStreams;
@@ -350,7 +341,9 @@ public class IrisComplex implements DataProvider {
                 preparedRegions,
                 (region, inferredType) -> compileInferredBiomeStream(engine, region, inferredType, emptyBiome)
         );
-        GeneratorGroup[] generatorGroups = freezeGeneratorGroups(generators);
+        GeneratorGroup[] generatorGroups = focusBiome == null && !buffetActive
+                ? contributingGroups(freezeGeneratorGroups(generators), baseCapableBiomes(preparedRegions))
+                : freezeGeneratorGroups(generators);
         int interpolatorCount = generatorGroups.length;
         frozenInterpolators = new IrisInterpolator[interpolatorCount];
         frozenGenerators = new IrisGenerator[interpolatorCount][];
@@ -384,8 +377,6 @@ public class IrisComplex implements DataProvider {
                 : GenerationStreams.cache2D(RegionSelection.select(new RegionSelection.Options(
                         engine.getDimension(), data, regionStyleStream, imageMapRuntime, null)),
                         "regionStream", engine, cacheSize);
-        regionIDStream = regionIdentityStream.convertCached((i) -> new UUID(Double.doubleToLongBits(i),
-                String.valueOf(i * 38445).hashCode() * 3245556666L));
         caveBiomeStream = GenerationStreams.cache2D(GenerationStreams.contextInjecting(regionStream, engine, (c, x, z) -> c.getRegion().get(x, z))
                 .convert((r) -> createInferredBiomeStream(r, InferredType.CAVE))
                 .convertAware2D(ProceduralStream::get), "caveBiomeStream", engine, cacheSize);
@@ -487,8 +478,6 @@ public class IrisComplex implements DataProvider {
         shoreSlopeStream = terrain3DEnabled ? baseTerrainHeightStream.slope(3) : naturalSlopeStream;
         trueBiomeStream = focusedBiomes != null ? GenerationStreams.cache2D(focusedBiomes, "trueBiomeStream-focus", engine, cacheSize) : GenerationStreams.cache2D(heightStream
                 .convertAware2D((terrainHeight, x, z) -> resolveHydrologySurfaceBiome(terrainHeight, x, z)), "trueBiomeStream", engine, cacheSize);
-        trueBiomeDerivativeStream = GenerationStreams.cache2D(GenerationStreams.contextInjecting(trueBiomeStream, engine, (c, x, z) -> c.getBiome().get(x, z))
-                .convert((b) -> IrisPlatforms.get().registries().biome(b.getDerivativeKey())), "trueBiomeDerivativeStream", engine, cacheSize);
         riverDistanceStream = GenerationStreams.cache2DDouble(ProceduralStream.ofDouble(this::resolveHydrologyDistance), "riverDistanceStream", engine, cacheSize);
         riverFlowStream = GenerationStreams.cache2DDouble(ProceduralStream.ofDouble(this::resolveHydrologyFlow), "riverFlowStream", engine, cacheSize);
         riverCarveWeightStream = GenerationStreams.cache2DDouble(ProceduralStream.ofDouble(this::resolveHydrologyCarveWeight), "riverCarveWeightStream", engine, cacheSize);
@@ -498,26 +487,6 @@ public class IrisComplex implements DataProvider {
                         riverWaterSurfaceStream.get(x, z)
                 )), "heightFluidStream", engine, cacheSize);
         maxHeightStream = ProceduralStream.ofDouble((x, z) -> height);
-        terrainSurfaceDecoration = GenerationStreams.cache2D(GenerationStreams.contextInjecting(trueBiomeStream, engine, (c, x, z) -> c.getBiome().get(x, z))
-                .convertAware2D((b, xx, zz) -> decorateFor(b, xx, zz, IrisDecorationPart.NONE)), "terrainSurfaceDecoration", engine, cacheSize);
-        terrainCeilingDecoration = GenerationStreams.cache2D(GenerationStreams.contextInjecting(trueBiomeStream, engine, (c, x, z) -> c.getBiome().get(x, z))
-                .convertAware2D((b, xx, zz) -> decorateFor(b, xx, zz, IrisDecorationPart.CEILING)), "terrainCeilingDecoration", engine, cacheSize);
-        terrainCaveSurfaceDecoration = GenerationStreams.cache2D(GenerationStreams.contextInjecting(caveBiomeStream, engine, (c, x, z) -> c.getCave().get(x, z))
-                .convertAware2D((b, xx, zz) -> decorateFor(b, xx, zz, IrisDecorationPart.NONE)), "terrainCaveSurfaceDecoration", engine, cacheSize);
-        terrainCaveCeilingDecoration = GenerationStreams.cache2D(GenerationStreams.contextInjecting(caveBiomeStream, engine, (c, x, z) -> c.getCave().get(x, z))
-                .convertAware2D((b, xx, zz) -> decorateFor(b, xx, zz, IrisDecorationPart.CEILING)), "terrainCaveCeilingDecoration", engine, cacheSize);
-        shoreSurfaceDecoration = GenerationStreams.cache2D(GenerationStreams.contextInjecting(trueBiomeStream, engine, (c, x, z) -> c.getBiome().get(x, z))
-                .convertAware2D((b, xx, zz) -> decorateFor(b, xx, zz, IrisDecorationPart.SHORE_LINE)), "shoreSurfaceDecoration", engine, cacheSize);
-        seaSurfaceDecoration = GenerationStreams.cache2D(GenerationStreams.contextInjecting(trueBiomeStream, engine, (c, x, z) -> c.getBiome().get(x, z))
-                .convertAware2D((b, xx, zz) -> decorateFor(b, xx, zz, IrisDecorationPart.SEA_SURFACE)), "seaSurfaceDecoration", engine, cacheSize);
-        seaFloorDecoration = GenerationStreams.cache2D(GenerationStreams.contextInjecting(trueBiomeStream, engine, (c, x, z) -> c.getBiome().get(x, z))
-                .convertAware2D((b, xx, zz) -> decorateFor(b, xx, zz, IrisDecorationPart.SEA_FLOOR)), "seaFloorDecoration", engine, cacheSize);
-        baseBiomeIDStream = GenerationStreams.cache2D(GenerationStreams.contextInjecting(trueBiomeStream, engine, (c, x, z) -> c.getBiome().get(x, z))
-                .convertAware2D((b, x, z) -> {
-                    UUID d = regionIDStream.get(x, z);
-                    return new UUID(b.getLoadKey().hashCode() * 818223L,
-                            d.hashCode());
-                }), "", engine, cacheSize);
         //@done
         TerrainTransformer transformer = engine.getDimension().getTerrainTransform() == null ? null
                 : TerrainTransformRegistry.discover().resolve(engine.getDimension().getTerrainTransform());
@@ -1415,6 +1384,10 @@ public class IrisComplex implements DataProvider {
         return false;
     }
 
+    public boolean isPlatformMainThread() {
+        return terrainEngine.getPlatformHooks().isMainThread();
+    }
+
     public ProceduralStream<Double> getRawHeightStream() {
         return heightStream;
     }
@@ -1629,24 +1602,6 @@ public class IrisComplex implements DataProvider {
         return proceduralTerrainHeight.sample(worldX, worldZ);
     }
 
-    private IrisDecorator decorateFor(IrisBiome b, double x, double z, IrisDecorationPart part) {
-        RNG rngc = new RNG(Cache.key(((int) x), ((int) z)));
-
-        for (IrisDecorator i : b.getDecorators()) {
-            if (!i.getPartOf().equals(part)) {
-                continue;
-            }
-
-            NativeBlockState block = i.getBlockData(b, rngc, x, z, data);
-
-            if (block != null) {
-                return i;
-            }
-        }
-
-        return null;
-    }
-
     private IrisBiome resolveHydrologySurfaceBiome(double terrainHeight, double x, double z) {
         HydrologyColumnSample sample = hydrologySample(x, z);
         HydrologyColumnLayer layer = sample == null ? null : sample.primarySurfaceLayer().orElse(null);
@@ -1730,6 +1685,33 @@ public class IrisComplex implements DataProvider {
         return bandTop + shoreMinimumWidth * Math.min(shoreSlopes.getDouble(x, z) / SLOPE_RUN, MAX_SHORE_BAND_GRADIENT);
     }
 
+    static boolean aboveShoreBand(
+            double height,
+            IrisRegion region,
+            double x,
+            double z,
+            double fluidHeight,
+            ProceduralStream<Double> shoreSlopes
+    ) {
+        if (region.getShoreMinimumWidth() <= 0) {
+            double minimum = region.getShoreHeightMin();
+            double maximum = region.getShoreHeightMax();
+            double lowestTop = fluidHeight + shoreHeightAt(minimum, maximum, SHORE_NOISE_LOWEST);
+            double highestTop = fluidHeight + shoreHeightAt(minimum, maximum, SHORE_NOISE_HIGHEST);
+            if (height > Math.max(lowestTop, highestTop)) {
+                return true;
+            }
+            if (height <= Math.min(lowestTop, highestTop)) {
+                return false;
+            }
+        }
+        return height > shoreBandTop(height, region, x, z, fluidHeight, shoreSlopes);
+    }
+
+    private static double shoreHeightAt(double minimum, double maximum, double noise) {
+        return minimum == maximum ? minimum : IrisInterpolation.lerp(minimum, maximum, noise);
+    }
+
     static IrisBiome resolveSurfaceBiome(
             double height,
             IrisBiome biome,
@@ -1745,13 +1727,15 @@ public class IrisComplex implements DataProvider {
         if (biome == null || region == null) {
             return biome;
         }
-        double shoreTop = shoreBandTop(height, region, x, z, fluidHeight, shoreSlopes);
 
-        if (height >= fluidHeight - 1 && height <= shoreTop && !biome.isShore()) {
+        if (height >= fluidHeight - 1 && !biome.isShore()) {
-            return shoreBiomes.get(x, z);
+            if (!aboveShoreBand(height, region, x, z, fluidHeight, shoreSlopes)) {
-        }
+                return shoreBiomes.get(x, z);
-
+            }
-        if (height > shoreTop && !biome.isLand()) {
+            if (!biome.isLand()) {
+                return landBiomes.get(x, z);
+            }
+        } else if (!biome.isLand() && aboveShoreBand(height, region, x, z, fluidHeight, shoreSlopes)) {
             return landBiomes.get(x, z);
         }
 
@@ -1911,13 +1895,92 @@ public class IrisComplex implements DataProvider {
             return h;
         }
 
+        int grid = biomeBoundsSamplingStep;
+        GridBoundsCache cache = gridBoundsCache.get();
+        if (!ChunkCorners.supports(grid) || cache.cornersInUse) {
+            for (int interpolatorIndex = 0; interpolatorIndex < frozenInterpolators.length; interpolatorIndex++) {
+                h += interpolateGenerators(engine, frozenInterpolators[interpolatorIndex], interpolatorIndex, frozenGenerators[interpolatorIndex], x, z, seed);
+            }
+            return h;
+        }
+
+        cache.cornersInUse = true;
+        try {
+            return cornerBlockHeight(cache, engine, grid, x, z, seed);
+        } finally {
+            cache.cornersInUse = false;
+        }
+    }
+
+    private double cornerBlockHeight(GridBoundsCache cache, Engine engine, int grid, double x, double z, long seed) {
+        double h = 0;
+        int xi = (int) Math.floor(x);
+        int zi = (int) Math.floor(z);
+        int gx = xi & ~(grid - 1);
+        int gz = zi & ~(grid - 1);
+        double fx = (x - gx) / grid;
+        double fz = (z - gz) / grid;
+        ChunkCorners corners = cache.chunkCorners(xi >> 4, zi >> 4, frozenInterpolators.length, grid);
+        int cornerX = (gx - corners.originX) / grid;
+        int cornerZ = (gz - corners.originZ) / grid;
+        int cell = cornerZ * corners.cellsPerAxis + cornerX;
+        long heightSeed = seed + 239945;
         for (int interpolatorIndex = 0; interpolatorIndex < frozenInterpolators.length; interpolatorIndex++) {
-            h += interpolateGenerators(engine, frozenInterpolators[interpolatorIndex], interpolatorIndex, frozenGenerators[interpolatorIndex], x, z, seed);
+            IrisGenerator[] generators = frozenGenerators[interpolatorIndex];
+            if (generators.length == 0) {
+                continue;
+            }
+            int state = corners.cellState(interpolatorIndex, cell);
+            if (state == ChunkCorners.SILENT) {
+                continue;
+            }
+            long b00 = cornerAt(cache, engine, corners, interpolatorIndex, cornerX, cornerZ);
+            long b10 = fx == 0D ? 0L : cornerAt(cache, engine, corners, interpolatorIndex, cornerX + 1, cornerZ);
+            long b01 = fz == 0D ? 0L : cornerAt(cache, engine, corners, interpolatorIndex, cornerX, cornerZ + 1);
+            long b11 = fx == 0D || fz == 0D ? 0L : cornerAt(cache, engine, corners, interpolatorIndex, cornerX + 1, cornerZ + 1);
+            if (state == ChunkCorners.UNKNOWN) {
+                corners.classify(interpolatorIndex, cornerX, cornerZ, cell);
+                if (silentBounds(b00) && silentBounds(b10) && silentBounds(b01) && silentBounds(b11)) {
+                    continue;
+                }
+            }
+            double lo;
+            double hi;
+            if (fx == 0D && fz == 0D) {
+                lo = boundsLow(b00);
+                hi = boundsHigh(b00);
+            } else if (fz == 0D) {
+                lo = biLerp(boundsLow(b00), boundsLow(b10), boundsLow(b00), boundsLow(b10), fx, fz);
+                hi = biLerp(boundsHigh(b00), boundsHigh(b10), boundsHigh(b00), boundsHigh(b10), fx, fz);
+            } else if (fx == 0D) {
+                lo = biLerp(boundsLow(b00), boundsLow(b00), boundsLow(b01), boundsLow(b01), fx, fz);
+                hi = biLerp(boundsHigh(b00), boundsHigh(b00), boundsHigh(b01), boundsHigh(b01), fx, fz);
+            } else {
+                lo = biLerp(boundsLow(b00), boundsLow(b10), boundsLow(b01), boundsLow(b11), fx, fz);
+                hi = biLerp(boundsHigh(b00), boundsHigh(b10), boundsHigh(b01), boundsHigh(b11), fx, fz);
+            }
+            h += averageGeneratorHeights(generators, lo, hi, x, z, heightSeed);
         }
 
         return h;
     }
 
+    private long cornerAt(GridBoundsCache cache, Engine engine, ChunkCorners corners, int interpolatorIndex, int column, int row) {
+        if (corners.known(interpolatorIndex, column, row)) {
+            return corners.corner(interpolatorIndex, column, row);
+        }
+        long packed = cornerBounds(cache, engine, frozenInterpolators[interpolatorIndex], interpolatorIndex,
+                frozenGenerators[interpolatorIndex], corners.originX + column * corners.grid, corners.originZ + row * corners.grid);
+        if (Double.isFinite(boundsLow(packed)) && Double.isFinite(boundsHigh(packed))) {
+            corners.remember(interpolatorIndex, column, row, packed);
+        }
+        return packed;
+    }
+
+    private static boolean silentBounds(long packed) {
+        return (packed & 0x7FFFFFFF7FFFFFFFL) == 0L;
+    }
+
     private NoiseBounds naturalHeightBounds(
             Engine engine,
             KList<IrisShapedGeneratorStyle> overlayNoise,
@@ -2058,6 +2121,48 @@ public class IrisComplex implements DataProvider {
         return groups;
     }
 
+    static GeneratorGroup[] contributingGroups(GeneratorGroup[] groups, Collection<IrisBiome> baseBiomes) {
+        List<GeneratorGroup> contributing = new ArrayList<>(groups.length);
+        for (GeneratorGroup group : groups) {
+            if (contributesHeight(group.generators(), baseBiomes)) {
+                contributing.add(group);
+            }
+        }
+        return contributing.toArray(new GeneratorGroup[0]);
+    }
+
+    private static boolean contributesHeight(IrisGenerator[] generators, Collection<IrisBiome> baseBiomes) {
+        for (IrisBiome biome : baseBiomes) {
+            GeneratorBounds bounds = computeGeneratorBounds(generators, biome);
+            if (bounds.min != 0D || bounds.max != 0D) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    private Collection<IrisBiome> baseCapableBiomes(KList<IrisRegion> regions) {
+        Set<IrisBiome> reached = Collections.newSetFromMap(new IdentityHashMap<>());
+        ArrayDeque<IrisBiome> pending = new ArrayDeque<>();
+        for (IrisRegion region : regions) {
+            pending.addAll(loadInferredBiomes(region.getLandBiomes(), InferredType.LAND));
+            pending.addAll(loadInferredBiomes(region.getSeaBiomes(), InferredType.SEA));
+        }
+        pending.addAll(imageMapRuntime.getMappedBiomes());
+        while (!pending.isEmpty()) {
+            IrisBiome biome = pending.poll();
+            if (!reached.add(biome)) {
+                continue;
+            }
+            for (IrisBiome child : biome.getRealChildren(this)) {
+                if (child != null) {
+                    pending.add(child);
+                }
+            }
+        }
+        return reached;
+    }
+
     static double averageGeneratorHeights(
             IrisGenerator[] generators,
             double low,
@@ -2103,7 +2208,7 @@ public class IrisComplex implements DataProvider {
         for (int i = 0; i < frozenInterpolators.length; i++) {
             IdentityHashMap<IrisBiome, GeneratorBounds> interpolatorBounds = new IdentityHashMap<>(Math.max(allBiomes.size(), 16));
             for (IrisBiome biome : allBiomes) {
-                interpolatorBounds.put(biome, computeGeneratorBounds(engine, frozenGenerators[i], biome));
+                interpolatorBounds.put(biome, computeGeneratorBounds(frozenGenerators[i], biome));
             }
             bounds.put(frozenInterpolators[i], interpolatorBounds);
         }
@@ -2111,7 +2216,7 @@ public class IrisComplex implements DataProvider {
         return bounds;
     }
 
-    private GeneratorBounds computeGeneratorBounds(Engine engine, IrisGenerator[] generators, IrisBiome biome) {
+    private static GeneratorBounds computeGeneratorBounds(IrisGenerator[] generators, IrisBiome biome) {
         double min = 0D;
         double max = 0D;
 
@@ -2145,7 +2250,7 @@ public class IrisComplex implements DataProvider {
             return local;
         }
 
-        GeneratorBounds computed = computeGeneratorBounds(engine, generators, biome);
+        GeneratorBounds computed = computeGeneratorBounds(generators, biome);
         localBounds.put(biome, computed);
         return computed;
     }
@@ -2246,6 +2351,27 @@ public class IrisComplex implements DataProvider {
         private final long[] packed = new long[GRID_BOUNDS_CACHE_SIZE];
         private final boolean[] valid = new boolean[GRID_BOUNDS_CACHE_SIZE];
         private final BoundsSampler sampler = new BoundsSampler();
+        private ChunkCorners recentCorners;
+        private ChunkCorners previousCorners;
+        private boolean cornersInUse;
+
+        private ChunkCorners chunkCorners(int chunkX, int chunkZ, int groups, int grid) {
+            ChunkCorners recent = recentCorners;
+            if (recent != null && recent.matches(chunkX, chunkZ, groups, grid)) {
+                return recent;
+            }
+            ChunkCorners previous = previousCorners;
+            if (previous != null && previous.matches(chunkX, chunkZ, groups, grid)) {
+                previousCorners = recent;
+                recentCorners = previous;
+                return previous;
+            }
+            ChunkCorners reused = previous != null && previous.fits(groups, grid) ? previous : new ChunkCorners(groups, grid);
+            reused.reset(chunkX, chunkZ);
+            previousCorners = recent;
+            recentCorners = reused;
+            return reused;
+        }
 
         private int slot(int cornerX, int cornerZ, int interpolatorIndex) {
             long h = (cornerX * 0x9E3779B97F4A7C15L) ^ (cornerZ * 0xC2B2AE3D27D4EB4FL) ^ (interpolatorIndex * 0x165667B19E3779F9L);
@@ -2254,6 +2380,92 @@ public class IrisComplex implements DataProvider {
         }
     }
 
+    private static final class ChunkCorners {
+        private static final int UNKNOWN = 0;
+        private static final int SILENT = 1;
+        private static final int ACTIVE = 2;
+
+        private final int groups;
+        private final int grid;
+        private final int cornersPerAxis;
+        private final int cellsPerAxis;
+        private final long[] packed;
+        private final boolean[] known;
+        private final byte[] cellStates;
+        private int chunkX;
+        private int chunkZ;
+        private int originX;
+        private int originZ;
+
+        private ChunkCorners(int groups, int grid) {
+            this.groups = groups;
+            this.grid = grid;
+            cellsPerAxis = 16 / grid;
+            cornersPerAxis = cellsPerAxis + 1;
+            packed = new long[groups * cornersPerAxis * cornersPerAxis];
+            known = new boolean[packed.length];
+            cellStates = new byte[groups * cellsPerAxis * cellsPerAxis];
+        }
+
+        private static boolean supports(int grid) {
+            return grid >= 2 && grid <= 16 && Integer.bitCount(grid) == 1;
+        }
+
+        private boolean fits(int groups, int grid) {
+            return this.groups == groups && this.grid == grid;
+        }
+
+        private boolean matches(int chunkX, int chunkZ, int groups, int grid) {
+            return this.chunkX == chunkX && this.chunkZ == chunkZ && fits(groups, grid);
+        }
+
+        private void reset(int chunkX, int chunkZ) {
+            this.chunkX = chunkX;
+            this.chunkZ = chunkZ;
+            originX = chunkX << 4;
+            originZ = chunkZ << 4;
+            Arrays.fill(known, false);
+            Arrays.fill(cellStates, (byte) UNKNOWN);
+        }
+
+        private int cellState(int group, int cell) {
+            return cellStates[group * cellsPerAxis * cellsPerAxis + cell];
+        }
+
+        private void setCellState(int group, int cell, int state) {
+            cellStates[group * cellsPerAxis * cellsPerAxis + cell] = (byte) state;
+        }
+
+        private boolean known(int group, int column, int row) {
+            return known[index(group, column, row)];
+        }
+
+        private long corner(int group, int column, int row) {
+            return packed[index(group, column, row)];
+        }
+
+        private void remember(int group, int column, int row, long value) {
+            int index = index(group, column, row);
+            packed[index] = value;
+            known[index] = true;
+        }
+
+        private void classify(int group, int column, int row, int cell) {
+            int first = index(group, column, row);
+            int second = first + cornersPerAxis;
+            if (!known[first] || !known[first + 1] || !known[second] || !known[second + 1]) {
+                return;
+            }
+            boolean silent = silentBounds(packed[first]) && silentBounds(packed[first + 1])
+                    && silentBounds(packed[second]) && silentBounds(packed[second + 1]);
+            setCellState(group, cell, silent ? SILENT : ACTIVE);
+        }
+
+        private int index(int group, int column, int row) {
+            return (group * cornersPerAxis + row) * cornersPerAxis + column;
+        }
+    }
+
     /**
      * Reusable per-thread bounds provider. Holds the biome memo and the lazily computed generator
      * bounds for one sampleBoundsRaw pass so the pass allocates nothing; {@link #bind}

core/src/main/java/art/arcane/iris/generation/stage/IrisTerrainNormalActuator.java

@@ -160,6 +160,7 @@ public class IrisTerrainNormalActuator extends EngineAssignedActuator<NativeBloc
         private final ChunkedDataCache<IrisBiome> biomeCache;
         private final ChunkedDataCache<IrisRegion> regionCache;
         private final ChunkedDataCache<NativeBlockState> rockCache;
+        private final ChunkedDataCache<NativeBlockState> fluidCache;
         private final UpperDimensionContext upperContext;
         private final IrisOreBands dimensionSurfaceOres;
         private final IrisOreBands dimensionUndergroundOres;
@@ -192,6 +193,7 @@ public class IrisTerrainNormalActuator extends EngineAssignedActuator<NativeBloc
             biomeCache = context.getBiome();
             regionCache = context.getRegion();
             rockCache = context.getRock();
+            fluidCache = context.getFluid();
             upperContext = getEngine().getUpperContext();
             dimensionSurfaceOres = hideOres ? IrisOreBands.EMPTY : dimension.getSurfaceOreBands();
             dimensionUndergroundOres = hideOres ? IrisOreBands.EMPTY : dimension.getUndergroundOreBands();
@@ -247,8 +249,10 @@ public class IrisTerrainNormalActuator extends EngineAssignedActuator<NativeBloc
             IrisRiverMaterialConfig roleMaterial = hydrologyRoleMaterial(
                     hydrologyTerrain, bedMaterial, shoreMaterial, bankMaterial);
             int paintDepth = roleMaterial == null ? 0 : roleMaterial.getDepth();
-            NativeBlockState fluid = hydrologyFluid == null || transitionDisplaced
+            NativeBlockState fluid = transitionDisplaced
                     ? complex.resolveSurfaceFluid(realX, realZ)
+                    : hydrologyFluid == null
+                    ? fluidCache.get(xf, zf)
                     : complex.resolveHydrologyFluid(hydrologyFluid.profileKey(), realX, realZ);
             NativeBlockState rock = rockCache.get(xf, zf);
             NativeBlockState mappedSurfaceBlock = complex.getImageMapRuntime().sampleSurfaceBlock(realX, realZ);

core/src/test/java/art/arcane/iris/generation/context/ChunkContextPrefillPlanTest.java

@@ -95,9 +95,42 @@ public class ChunkContextPrefillPlanTest {
     }
 
     @Test
-    public void singleOrNoFillTaskPrefillsInline() {
+    public void generationWorkersPrefillInlineWithoutConsultingSharedExecutor() {
-        assertFalse(ChunkContext.shouldPrefillAsync(ChunkContext.PrefillPlan.NO_CAVE, 0));
+        try (MockedStatic<IrisPlatforms> platforms = mockStatic(IrisPlatforms.class)) {
-        assertFalse(ChunkContext.shouldPrefillAsync(ChunkContext.PrefillPlan.NO_CAVE, 1));
+            platforms.when(IrisPlatforms::isBound).thenReturn(true);
+            assertFalse(ChunkContext.shouldPrefillAsync(ChunkContext.PrefillPlan.NO_CAVE, false));
+            assertFalse(ChunkContext.shouldPrefillAsync(ChunkContext.PrefillPlan.ALL, false));
+            platforms.verifyNoInteractions();
+        }
+    }
+
+    @Test
+    public void platformMainThreadKeepsBlockingPrefillOffTheTickThread() {
+        try (MockedStatic<IrisPlatforms> platforms = mockStatic(IrisPlatforms.class)) {
+            platforms.when(IrisPlatforms::isBound).thenReturn(true);
+            assertTrue(ChunkContext.shouldPrefillAsync(ChunkContext.PrefillPlan.NO_CAVE, true));
+            assertFalse(ChunkContext.shouldPrefillAsync(ChunkContext.PrefillPlan.NONE, true));
+            assertFalse(ChunkContext.shouldPrefillAsync(ChunkContext.PrefillPlan.NATURAL_TERRAIN, true));
+        }
+    }
+
+    @Test
+    public void inlinePrefillFinishesHeightsBeforeTheBiomePassStarts() {
+        AtomicInteger caveCalls = new AtomicInteger();
+        AtomicInteger heightCalls = new AtomicInteger();
+        AtomicInteger biomeCalls = new AtomicInteger();
+        AtomicInteger rockCalls = new AtomicInteger();
+        AtomicInteger fluidCalls = new AtomicInteger();
+        AtomicInteger regionCalls = new AtomicInteger();
+        AtomicInteger heightsSeenByFirstBiome = new AtomicInteger(-1);
+        try (MockedStatic<IrisPlatforms> platforms = mockStatic(IrisPlatforms.class)) {
+            platforms.when(IrisPlatforms::isBound).thenReturn(true);
+            createContext(ChunkContext.PrefillPlan.NO_CAVE, caveCalls, heightCalls, biomeCalls, rockCalls,
+                    fluidCalls, regionCalls, null, () -> heightsSeenByFirstBiome.compareAndSet(-1, heightCalls.get()));
+        }
+
+        assertEquals(256, heightsSeenByFirstBiome.get());
+        assertEquals(256, biomeCalls.get());
     }
 
     @Test
@@ -110,7 +143,7 @@ public class ChunkContextPrefillPlanTest {
         AtomicInteger regionCalls = new AtomicInteger();
         try (MockedStatic<IrisPlatforms> platforms = mockStatic(IrisPlatforms.class)) {
             platforms.when(IrisPlatforms::isBound).thenReturn(true);
-            assertFalse(ChunkContext.shouldPrefillAsync(ChunkContext.PrefillPlan.NATURAL_TERRAIN, 5));
+            assertFalse(ChunkContext.shouldPrefillAsync(ChunkContext.PrefillPlan.NATURAL_TERRAIN, true));
             ChunkContext context = createContext(ChunkContext.PrefillPlan.NATURAL_TERRAIN,
                     caveCalls, heightCalls, biomeCalls, rockCalls, fluidCalls, regionCalls);
 
@@ -228,6 +261,22 @@ public class ChunkContextPrefillPlanTest {
             AtomicInteger fluidCalls,
             AtomicInteger regionCalls,
             IrisHydrologyRuntime runtime
+    ) {
+        return createContext(prefillPlan, caveCalls, heightCalls, biomeCalls, rockCalls, fluidCalls, regionCalls,
+                runtime, () -> {
+                });
+    }
+
+    private ChunkContext createContext(
+            ChunkContext.PrefillPlan prefillPlan,
+            AtomicInteger caveCalls,
+            AtomicInteger heightCalls,
+            AtomicInteger biomeCalls,
+            AtomicInteger rockCalls,
+            AtomicInteger fluidCalls,
+            AtomicInteger regionCalls,
+            IrisHydrologyRuntime runtime,
+            Runnable biomeObserver
     ) {
         IrisComplex complex = mock(IrisComplex.class);
 
@@ -244,6 +293,7 @@ public class ChunkContextPrefillPlanTest {
         ProceduralStream<IrisBiome> biomeStream = mock(ProceduralStream.class);
         IrisBiome biome = mock(IrisBiome.class);
         doAnswer(invocation -> {
+            biomeObserver.run();
             biomeCalls.incrementAndGet();
             return biome;
         }).when(biomeStream).get(anyDouble(), anyDouble());

core/src/test/java/art/arcane/iris/generation/runtime/DimensionTerrain3DCompositionTest.java

@@ -351,6 +351,7 @@ public class DimensionTerrain3DCompositionTest {
         when(context.getBiome()).thenReturn(biomes);
         when(context.getRegion()).thenReturn(regions);
         when(context.getRock()).thenReturn(rocks);
+        when(context.getFluid()).thenReturn(mock(ChunkedDataCache.class));
         when(context.getRoundedHeight(0, 0)).thenReturn(rootHeight);
         Hunk<NativeBlockState> blocks = Hunk.newArrayHunk(1, 64, 1);
         new IrisTerrainNormalActuator(engine).paint(0, 0, blocks, context);

core/src/test/java/art/arcane/iris/generation/runtime/IrisComplexChunkCornersTest.java

@@ -0,0 +1,289 @@
+package art.arcane.iris.generation.runtime;
+
+import art.arcane.iris.generation.noise.IrisGenerator;
+import art.arcane.iris.generation.noise.IrisInterpolator;
+import art.arcane.volmlib.util.interpolation.NoiseBounds;
+import art.arcane.volmlib.util.interpolation.NoiseBoundsProvider;
+import org.junit.Test;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.HashMap;
+import java.util.SplittableRandom;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+import static org.mockito.Answers.CALLS_REAL_METHODS;
+import static org.mockito.Mockito.mock;
+
+public class IrisComplexChunkCornersTest {
+    @Test
+    public void chunkCornerHeightsMatchPerGroupGridSamplingBitForBit() throws Exception {
+        for (int step : new int[]{2, 4, 8, 16}) {
+            IrisInterpolator[] interpolators = {
+                    new PatchInterpolator(0, 1D),
+                    new PatchInterpolator(1, -3D),
+                    new ZeroInterpolator(true),
+                    new PatchInterpolator(2, 0.5D),
+                    new ZeroInterpolator(false)
+            };
+            IrisGenerator[][] generators = {
+                    {new WaveGenerator(1D), new WaveGenerator(0.5D)},
+                    {new WaveGenerator(-0.25D)},
+                    {new WaveGenerator(2D)},
+                    {new WaveGenerator(0.75D), new WaveGenerator(-1D), new WaveGenerator(0.125D)},
+                    {new WaveGenerator(4D)}
+            };
+            IrisComplex candidate = createComplex(step, interpolators, generators);
+            IrisComplex reference = createComplex(step, interpolators, generators);
+            SplittableRandom random = new SplittableRandom(step * 31L);
+            for (int sample = 0; sample < 60_000; sample++) {
+                double x = coordinate(random);
+                double z = coordinate(random);
+                assertEquals("step " + step + " at " + x + "," + z,
+                        Double.doubleToRawLongBits(expectedHeight(reference, interpolators, generators, x, z)),
+                        Double.doubleToRawLongBits(interpolatedHeight(candidate, x, z)));
+            }
+        }
+    }
+
+    @Test
+    public void silentCellsNeverEvaluateTheirGenerators() throws Exception {
+        WaveGenerator quiet = new WaveGenerator(1D);
+        WaveGenerator loud = new WaveGenerator(1D);
+        IrisInterpolator[] interpolators = {new ZeroInterpolator(true), new PatchInterpolator(0, 2D)};
+        IrisGenerator[][] generators = {{quiet}, {loud}};
+        IrisComplex complex = createComplex(4, interpolators, generators);
+
+        for (int x = 0; x < 64; x++) {
+            for (int z = 0; z < 64; z++) {
+                interpolatedHeight(complex, x, z);
+            }
+        }
+
+        assertEquals(0, quiet.invocations);
+        assertTrue(loud.invocations > 0);
+    }
+
+    @Test
+    public void sparseSamplesFetchOnlyTheCornersTheirColumnsUse() throws Exception {
+        CountingInterpolator counting = new CountingInterpolator();
+        IrisInterpolator[] interpolators = {counting};
+        IrisGenerator[][] generators = {{new WaveGenerator(1D)}};
+        IrisComplex complex = createComplex(4, interpolators, generators);
+
+        for (int sample = 0; sample < 32; sample++) {
+            interpolatedHeight(complex, sample * 64D, sample * -64D);
+        }
+        assertEquals(32, counting.calls);
+
+        interpolatedHeight(complex, 2048D + 1D, 0D);
+        assertEquals(34, counting.calls);
+        interpolatedHeight(complex, 4096D, 1D);
+        assertEquals(36, counting.calls);
+        interpolatedHeight(complex, 8192D + 1D, 1D);
+        assertEquals(40, counting.calls);
+    }
+
+    @Test
+    public void nestedHeightSamplesLeaveTheOuterChunkBlockIntact() throws Exception {
+        ReentrantGenerator reentrant = new ReentrantGenerator();
+        IrisInterpolator[] interpolators = {new ZeroFreeInterpolator(), new PatchInterpolator(4, -2D)};
+        IrisGenerator[][] generators = {{reentrant}, {new WaveGenerator(0.5D)}};
+        IrisComplex candidate = createComplex(4, interpolators, generators);
+        IrisComplex reference = createComplex(4, interpolators, generators);
+        SplittableRandom random = new SplittableRandom(99L);
+        for (int sample = 0; sample < 4_000; sample++) {
+            double x = coordinate(random);
+            double z = coordinate(random);
+            reentrant.target = reference;
+            double expected = expectedHeight(reference, interpolators, generators, x, z);
+            reentrant.target = candidate;
+            assertEquals(Double.doubleToRawLongBits(expected), Double.doubleToRawLongBits(interpolatedHeight(candidate, x, z)));
+        }
+    }
+
+    @Test
+    public void nonFiniteCornersFailTheSameWayAndAreRetried() throws Exception {
+        NaNCornerInterpolator interpolator = new NaNCornerInterpolator();
+        IrisInterpolator[] interpolators = {interpolator};
+        IrisGenerator[][] generators = {{new WaveGenerator(1D)}};
+        IrisComplex complex = createComplex(4, interpolators, generators);
+
+        for (int attempt = 0; attempt < 2; attempt++) {
+            try {
+                interpolatedHeight(complex, 2D, 2D);
+                fail("A non-finite corner must fail the column");
+            } catch (InvocationTargetException expected) {
+                assertTrue(expected.getCause() instanceof IllegalStateException);
+            }
+        }
+        assertEquals(2, interpolator.nanCalls);
+        IrisComplex reference = createComplex(4, interpolators, generators);
+        assertEquals(Double.doubleToRawLongBits(expectedHeight(reference, interpolators, generators, 0D, 0D)),
+                Double.doubleToRawLongBits(interpolatedHeight(complex, 0D, 0D)));
+    }
+
+    private static double coordinate(SplittableRandom random) {
+        int base = random.nextInt(-80, 80);
+        return switch (random.nextInt(4)) {
+            case 0 -> base;
+            case 1 -> base + random.nextInt(4) * 0.25D;
+            case 2 -> base + random.nextDouble();
+            default -> base * 1031 + random.nextInt(-3, 3);
+        };
+    }
+
+    private static double expectedHeight(
+            IrisComplex complex,
+            IrisInterpolator[] interpolators,
+            IrisGenerator[][] generators,
+            double x,
+            double z
+    ) throws Exception {
+        Method interpolate = IrisComplex.class.getDeclaredMethod("interpolateGenerators", Engine.class,
+                IrisInterpolator.class, int.class, IrisGenerator[].class, double.class, double.class, long.class);
+        interpolate.setAccessible(true);
+        double height = 0;
+        for (int group = 0; group < interpolators.length; group++) {
+            height += (double) interpolate.invoke(complex, null, interpolators[group], group, generators[group], x, z, 31L);
+        }
+        return height;
+    }
+
+    private static double interpolatedHeight(IrisComplex complex, double x, double z) throws Exception {
+        Method method = IrisComplex.class.getDeclaredMethod("getInterpolatedHeight", Engine.class,
+                double.class, double.class, long.class);
+        method.setAccessible(true);
+        return (double) method.invoke(complex, null, x, z, 31L);
+    }
+
+    private static IrisComplex createComplex(int step, IrisInterpolator[] interpolators, IrisGenerator[][] generators) throws Exception {
+        IrisComplex complex = mock(IrisComplex.class, CALLS_REAL_METHODS);
+        setField(complex, "biomeBoundsSamplingStep", step);
+        setField(complex, "generatorBounds", new HashMap<>());
+        setField(complex, "biomeBuffetGenerators", new HashMap<>());
+        setField(complex, "frozenInterpolators", interpolators);
+        setField(complex, "frozenGenerators", generators);
+        Class<?> cacheClass = Class.forName("art.arcane.iris.generation.runtime.IrisComplex$GridBoundsCache");
+        Constructor<?> cacheConstructor = cacheClass.getDeclaredConstructor();
+        cacheConstructor.setAccessible(true);
+        setField(complex, "gridBoundsCache", ThreadLocal.withInitial(() -> newCache(cacheConstructor)));
+        return complex;
+    }
+
+    private static Object newCache(Constructor<?> constructor) {
+        try {
+            return constructor.newInstance();
+        } catch (ReflectiveOperationException e) {
+            throw new IllegalStateException(e);
+        }
+    }
+
+    private static void setField(IrisComplex complex, String name, Object value) throws Exception {
+        Field field = IrisComplex.class.getDeclaredField(name);
+        field.setAccessible(true);
+        field.set(complex, value);
+    }
+
+    private static final class PatchInterpolator extends IrisInterpolator {
+        private final int salt;
+        private final double scale;
+
+        private PatchInterpolator(int salt, double scale) {
+            this.salt = salt;
+            this.scale = scale;
+        }
+
+        @Override
+        public NoiseBounds interpolateBounds(double x, double z, NoiseBoundsProvider provider) {
+            long cell = Math.floorDiv((long) x, 24L) * 73_856_093L ^ Math.floorDiv((long) z, 24L) * 19_349_663L ^ salt * 83_492_791L;
+            if (Math.floorMod(cell, 3L) != 0L) {
+                return new NoiseBounds(0D, 0D);
+            }
+            double low = (x * 0.0625D - z * 0.03125D) * scale;
+            return new NoiseBounds(low, low + 3.75D * scale + Math.floorMod(cell, 5L));
+        }
+    }
+
+    private static final class ZeroFreeInterpolator extends IrisInterpolator {
+        @Override
+        public NoiseBounds interpolateBounds(double x, double z, NoiseBoundsProvider provider) {
+            return new NoiseBounds(x * 0.01D - 1D, z * 0.01D + 3D);
+        }
+    }
+
+    private static final class ZeroInterpolator extends IrisInterpolator {
+        private final boolean negative;
+
+        private ZeroInterpolator(boolean negative) {
+            this.negative = negative;
+        }
+
+        @Override
+        public NoiseBounds interpolateBounds(double x, double z, NoiseBoundsProvider provider) {
+            return negative ? new NoiseBounds(-0D, 0D) : new NoiseBounds(0D, -0D);
+        }
+    }
+
+    private static final class CountingInterpolator extends IrisInterpolator {
+        private int calls;
+
+        @Override
+        public NoiseBounds interpolateBounds(double x, double z, NoiseBoundsProvider provider) {
+            calls++;
+            return new NoiseBounds(x * 0.001D, x * 0.001D + 2D);
+        }
+    }
+
+    private static final class NaNCornerInterpolator extends IrisInterpolator {
+        private int nanCalls;
+
+        @Override
+        public NoiseBounds interpolateBounds(double x, double z, NoiseBoundsProvider provider) {
+            if (x == 4D && z == 4D) {
+                nanCalls++;
+                return new NoiseBounds(Double.NaN, 1D);
+            }
+            return new NoiseBounds(0.25D, 0.5D);
+        }
+    }
+
+    private static final class ReentrantGenerator extends IrisGenerator {
+        private IrisComplex target;
+        private boolean nested;
+
+        @Override
+        public double getHeight(double x, double z, long seed) {
+            if (nested) {
+                return Math.cos(x * 0.13D) * 0.5D;
+            }
+            nested = true;
+            try {
+                return (interpolatedHeight(target, x + 4099D, z - 2053D) + interpolatedHeight(target, x - 8191D, z + 1031D)) * 0.001D;
+            } catch (Exception e) {
+                throw new IllegalStateException(e);
+            } finally {
+                nested = false;
+            }
+        }
+    }
+
+    private static final class WaveGenerator extends IrisGenerator {
+        private final double amplitude;
+        private int invocations;
+
+        private WaveGenerator(double amplitude) {
+            this.amplitude = amplitude;
+        }
+
+        @Override
+        public double getHeight(double x, double z, long seed) {
+            invocations++;
+            return Math.sin(x * 0.37D + seed) * Math.cos(z * 0.21D) * amplitude;
+        }
+    }
+}

core/src/test/java/art/arcane/iris/generation/runtime/IrisComplexContributingGroupsTest.java

@@ -0,0 +1,85 @@
+package art.arcane.iris.generation.runtime;
+
+import art.arcane.iris.generation.biome.IrisBiome;
+import art.arcane.iris.generation.biome.IrisBiomeGeneratorLink;
+import art.arcane.iris.generation.noise.IrisGenerator;
+import art.arcane.iris.generation.noise.IrisInterpolator;
+import art.arcane.volmlib.util.collection.KList;
+import art.arcane.volmlib.util.interpolation.InterpolationMethod;
+import org.junit.Test;
+
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertSame;
+
+public class IrisComplexContributingGroupsTest {
+    @Test
+    public void groupsWithZeroBoundsInEveryBaseBiomeAreDropped() {
+        IrisComplex.GeneratorGroup flat = group(InterpolationMethod.BILINEAR_STARCAST_6, 7D, "default");
+        IrisComplex.GeneratorGroup hills = group(InterpolationMethod.BILINEAR_STARCAST_9, 12D, "hills", "cliffs");
+        IrisComplex.GeneratorGroup shoreOnly = group(InterpolationMethod.BILINEAR_STARCAST_3, 30D, "ocean");
+        IrisBiome plains = biome(link("default", 0, 0), link("hills", -4, 12));
+        IrisBiome desert = biome(link("default", 0, 0), link("cliffs", 0, 3));
+
+        IrisComplex.GeneratorGroup[] contributing = IrisComplex.contributingGroups(
+                new IrisComplex.GeneratorGroup[]{flat, hills, shoreOnly}, List.of(plains, desert));
+
+        assertEquals(1, contributing.length);
+        assertSame(hills, contributing[0]);
+    }
+
+    @Test
+    public void aNegativeOnlyOrMaximumOnlyLinkKeepsItsGroup() {
+        IrisComplex.GeneratorGroup sinks = group(InterpolationMethod.BILINEAR, 16D, "sinks");
+        IrisComplex.GeneratorGroup peaks = group(InterpolationMethod.STARCAST_12, 42D, "peaks");
+
+        IrisComplex.GeneratorGroup[] contributing = IrisComplex.contributingGroups(
+                new IrisComplex.GeneratorGroup[]{sinks, peaks},
+                List.of(biome(link("sinks", -6, 0)), biome(link("peaks", 0, 9))));
+
+        assertEquals(2, contributing.length);
+        assertSame(sinks, contributing[0]);
+        assertSame(peaks, contributing[1]);
+    }
+
+    @Test
+    public void linksThatCancelAcrossGeneratorsSumToZeroBoundsAndAreDropped() {
+        IrisComplex.GeneratorGroup pair = group(InterpolationMethod.BILINEAR_STARCAST_9, 52D, "rise", "fall");
+
+        IrisComplex.GeneratorGroup[] contributing = IrisComplex.contributingGroups(
+                new IrisComplex.GeneratorGroup[]{pair},
+                List.of(biome(link("rise", -5, 5), link("fall", 5, -5))));
+
+        assertEquals(0, contributing.length);
+    }
+
+    @Test
+    public void noBaseBiomesDropsEveryGroup() {
+        IrisComplex.GeneratorGroup hills = group(InterpolationMethod.BILINEAR_STARCAST_9, 12D, "hills");
+
+        assertEquals(0, IrisComplex.contributingGroups(new IrisComplex.GeneratorGroup[]{hills}, List.of()).length);
+    }
+
+    private static IrisComplex.GeneratorGroup group(InterpolationMethod function, double scale, String... keys) {
+        IrisInterpolator interpolator = new IrisInterpolator().setFunction(function).setHorizontalScale(scale);
+        IrisGenerator[] generators = new IrisGenerator[keys.length];
+        for (int index = 0; index < keys.length; index++) {
+            IrisGenerator generator = new IrisGenerator();
+            generator.setLoadKey(keys[index]);
+            generator.setInterpolator(interpolator);
+            generators[index] = generator;
+        }
+        return new IrisComplex.GeneratorGroup(interpolator, generators);
+    }
+
+    private static IrisBiome biome(IrisBiomeGeneratorLink... links) {
+        IrisBiome biome = new IrisBiome();
+        biome.setGenerators(new KList<>(List.of(links)));
+        return biome;
+    }
+
+    private static IrisBiomeGeneratorLink link(String generator, int min, int max) {
+        return new IrisBiomeGeneratorLink().setGenerator(generator).setMin(min).setMax(max);
+    }
+}

core/src/test/java/art/arcane/iris/generation/runtime/IrisComplexShoreBandTest.java

@@ -0,0 +1,207 @@
+package art.arcane.iris.generation.runtime;
+
+import art.arcane.iris.generation.biome.IrisBiome;
+import art.arcane.iris.generation.terrain.IrisRegion;
+import art.arcane.volmlib.util.collection.KList;
+import art.arcane.volmlib.util.noise.CNG;
+import art.arcane.volmlib.util.noise.OffsetNoiseGenerator;
+import art.arcane.volmlib.util.noise.SimplexNoise;
+import art.arcane.volmlib.util.stream.ProceduralStream;
+import org.junit.Test;
+
+import java.util.SplittableRandom;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.ArgumentMatchers.anyDouble;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.doThrow;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.withSettings;
+
+public class IrisComplexShoreBandTest {
+    private static final double[] SHORE_EXTREMES = {0D, 1.2D, 3.2D, 2.5D, 7.75D, -1.5D, 4D, 0.0001D, 63.9D};
+
+    @Test
+    public void shoreHeightGeneratorIsAnIdentityPostSimplexSignature() {
+        for (int sample = 0; sample < 8; sample++) {
+            CNG generator = region(sample).getShoreHeightGenerator();
+            assertTrue(generator.getGenerator() instanceof OffsetNoiseGenerator);
+            assertTrue(((OffsetNoiseGenerator) generator.getGenerator()).getBase() instanceof SimplexNoise);
+            assertEquals(1D, generator.getOpacity(), 0D);
+            assertTrue(generator.getChildren() == null || generator.getChildren().isEmpty());
+            assertEquals(1D, generator.getPower(), 0D);
+            assertEquals(0D, generator.getUp(), 0D);
+            assertEquals(0D, generator.getDown(), 0D);
+            assertEquals(1D, generator.getPatch(), 0D);
+            assertNull(generator.getCache());
+            assertNull(generator.getCustomGenerator());
+        }
+    }
+
+    @Test
+    public void simplexAmplitudeBoundFitsInsideTheShoreNoiseRange() {
+        double kernelPeak = 0D;
+        for (int step = 0; step <= 2_000_000; step++) {
+            double radius = Math.sqrt(0.5D) * step / 2_000_000D;
+            double falloff = 0.5D - radius * radius;
+            kernelPeak = Math.max(kernelPeak, falloff * falloff * falloff * falloff * Math.sqrt(2D) * radius);
+        }
+        assertEquals(256D / 19683D, kernelPeak, 1e-9D);
+        double amplitude = 50D * 3D * 256D / 19683D;
+        assertTrue(0.5D + amplitude / 2D < IrisComplex.SHORE_NOISE_HIGHEST);
+        assertTrue(0.5D - amplitude / 2D > IrisComplex.SHORE_NOISE_LOWEST);
+    }
+
+    @Test
+    public void shoreHeightNoiseStaysInsideTheProvenRange() {
+        SplittableRandom random = new SplittableRandom(1337L);
+        double lowest = Double.POSITIVE_INFINITY;
+        double highest = Double.NEGATIVE_INFINITY;
+        for (int sample = 0; sample < 4; sample++) {
+            CNG generator = region(sample).getShoreHeightGenerator();
+            for (int point = 0; point < 250_000; point++) {
+                double scale = point % 2 == 0 ? 1D : 64D;
+                double noise = generator.noise(random.nextDouble(-1e6D, 1e6D) / scale, random.nextDouble(-1e6D, 1e6D) / scale);
+                lowest = Math.min(lowest, noise);
+                highest = Math.max(highest, noise);
+            }
+        }
+        assertTrue("lowest " + lowest, lowest >= IrisComplex.SHORE_NOISE_LOWEST);
+        assertTrue("highest " + highest, highest <= IrisComplex.SHORE_NOISE_HIGHEST);
+    }
+
+    @Test
+    public void lazyShoreBandMatchesTheEagerBandTop() {
+        SplittableRandom random = new SplittableRandom(42L);
+        ProceduralStream<Double> slopes = ProceduralStream.ofDouble((x, z) -> 2D);
+        for (int sample = 0; sample < 400_000; sample++) {
+            IrisRegion region = region(random.nextInt(64))
+                    .setShoreHeightMin(SHORE_EXTREMES[random.nextInt(SHORE_EXTREMES.length)])
+                    .setShoreHeightMax(SHORE_EXTREMES[random.nextInt(SHORE_EXTREMES.length)])
+                    .setShoreHeightZoom(random.nextBoolean() ? 3.14D : 0.15D)
+                    .setShoreMinimumWidth(random.nextInt(8) == 0 ? 2D : 0D);
+            double fluid = random.nextInt(4) == 0 ? 63D : random.nextInt(-64, 200);
+            double height = random.nextInt(3) == 0
+                    ? fluid + random.nextDouble(-3D, 9D)
+                    : random.nextInt(-64, 320) + (random.nextBoolean() ? 0D : random.nextDouble());
+            double x = random.nextInt(-30_000_000, 30_000_000);
+            double z = random.nextInt(-30_000_000, 30_000_000);
+            boolean eager = height > IrisComplex.shoreBandTop(height, region, x, z, fluid, slopes);
+            assertEquals(eager, IrisComplex.aboveShoreBand(height, region, x, z, fluid, slopes));
+        }
+    }
+
+    @Test
+    public void lazySurfaceBiomeMatchesTheEagerSelection() {
+        SplittableRandom random = new SplittableRandom(7L);
+        IrisBiome land = mock(IrisBiome.class, withSettings().stubOnly());
+        IrisBiome sea = mock(IrisBiome.class, withSettings().stubOnly());
+        IrisBiome shore = mock(IrisBiome.class, withSettings().stubOnly());
+        IrisBiome[] bases = new IrisBiome[8];
+        for (int flags = 0; flags < bases.length; flags++) {
+            IrisBiome base = mock(IrisBiome.class, withSettings().stubOnly());
+            doReturn((flags & 1) != 0).when(base).isShore();
+            doReturn((flags & 2) != 0).when(base).isLand();
+            doReturn((flags & 4) != 0).when(base).isAquatic();
+            bases[flags] = base;
+        }
+        ProceduralStream<IrisBiome> lands = constant(land);
+        ProceduralStream<IrisBiome> seas = constant(sea);
+        ProceduralStream<IrisBiome> shores = constant(shore);
+        ProceduralStream<Double> slopes = ProceduralStream.ofDouble((x, z) -> 4D);
+        for (int sample = 0; sample < 200_000; sample++) {
+            IrisRegion region = region(random.nextInt(16))
+                    .setShoreHeightMin(SHORE_EXTREMES[random.nextInt(SHORE_EXTREMES.length)])
+                    .setShoreHeightMax(SHORE_EXTREMES[random.nextInt(SHORE_EXTREMES.length)])
+                    .setShoreMinimumWidth(random.nextInt(8) == 0 ? 3D : 0D);
+            double fluid = 63D;
+            double height = random.nextBoolean() ? fluid + random.nextInt(-3, 8) : random.nextInt(-64, 320);
+            double x = random.nextInt(-100_000, 100_000);
+            double z = random.nextInt(-100_000, 100_000);
+            IrisBiome base = bases[random.nextInt(bases.length)];
+            IrisBiome expected = eagerSurfaceBiome(height, base, region, x, z, fluid, lands, seas, shores, slopes);
+            assertSame(expected, IrisComplex.resolveSurfaceBiome(height, base, region, x, z, fluid, lands, seas, shores, slopes));
+        }
+    }
+
+    @Test
+    public void columnsOutsideTheShoreWindowNeverSampleTheShoreNoise() {
+        IrisRegion region = mock(IrisRegion.class);
+        doReturn(1.2D).when(region).getShoreHeightMin();
+        doReturn(3.2D).when(region).getShoreHeightMax();
+        doReturn(0D).when(region).getShoreMinimumWidth();
+        doThrow(new AssertionError("The shore noise was sampled for a column outside the shore window"))
+                .when(region).getShoreHeight(anyDouble(), anyDouble());
+        ProceduralStream<Double> slopes = ProceduralStream.ofDouble((x, z) -> 0D);
+
+        assertTrue(IrisComplex.aboveShoreBand(68D, region, 3D, 4D, 63D, slopes));
+        assertTrue(IrisComplex.aboveShoreBand(250D, region, 3D, 4D, 63D, slopes));
+        assertFalse(IrisComplex.aboveShoreBand(63.2D, region, 3D, 4D, 63D, slopes));
+        assertFalse(IrisComplex.aboveShoreBand(-20D, region, 3D, 4D, 63D, slopes));
+    }
+
+    @Test
+    public void equalShoreExtremesNeverSampleTheShoreNoise() {
+        IrisRegion region = mock(IrisRegion.class);
+        doReturn(2D).when(region).getShoreHeightMin();
+        doReturn(2D).when(region).getShoreHeightMax();
+        doReturn(0D).when(region).getShoreMinimumWidth();
+        doThrow(new AssertionError("Equal shore extremes need no shore noise"))
+                .when(region).getShoreHeight(anyDouble(), anyDouble());
+        ProceduralStream<Double> slopes = ProceduralStream.ofDouble((x, z) -> 0D);
+
+        assertFalse(IrisComplex.aboveShoreBand(65D, region, 3D, 4D, 63D, slopes));
+        assertTrue(IrisComplex.aboveShoreBand(65.0001D, region, 3D, 4D, 63D, slopes));
+    }
+
+    private static IrisRegion region(int variant) {
+        IrisRegion region = new IrisRegion();
+        region.setName("Shore Region " + variant);
+        region.setLandBiomeZoom(1D + variant * 0.25D);
+        KList<String> lands = new KList<>();
+        for (int index = 0; index < variant % 5; index++) {
+            lands.add("land-" + index);
+        }
+        region.setLandBiomes(lands);
+        return region;
+    }
+
+    private static IrisBiome eagerSurfaceBiome(
+            double height,
+            IrisBiome biome,
+            IrisRegion region,
+            double x,
+            double z,
+            double fluidHeight,
+            ProceduralStream<IrisBiome> landBiomes,
+            ProceduralStream<IrisBiome> seaBiomes,
+            ProceduralStream<IrisBiome> shoreBiomes,
+            ProceduralStream<Double> shoreSlopes
+    ) {
+        double shoreTop = IrisComplex.shoreBandTop(height, region, x, z, fluidHeight, shoreSlopes);
+        if (height >= fluidHeight - 1 && height <= shoreTop && !biome.isShore()) {
+            return shoreBiomes.get(x, z);
+        }
+        if (height > shoreTop && !biome.isLand()) {
+            return landBiomes.get(x, z);
+        }
+        if (height < fluidHeight && !biome.isAquatic()) {
+            return seaBiomes.get(x, z);
+        }
+        if (height == fluidHeight && !biome.isShore()) {
+            return shoreBiomes.get(x, z);
+        }
+        return biome;
+    }
+
+    private static ProceduralStream<IrisBiome> constant(IrisBiome biome) {
+        @SuppressWarnings("unchecked")
+        ProceduralStream<IrisBiome> stream = mock(ProceduralStream.class, withSettings().stubOnly());
+        doReturn(biome).when(stream).get(anyDouble(), anyDouble());
+        return stream;
+    }
+}

core/src/test/java/art/arcane/iris/generation/runtime/IrisComplexSurfaceBiomeTest.java

@@ -119,6 +119,8 @@ public class IrisComplexSurfaceBiomeTest {
         doReturn(false).when(base).isShore();
         doReturn(false).when(base).isAquatic();
         doReturn(3D).when(region).getShoreHeight(12D, 18D);
+        doReturn(1D).when(region).getShoreHeightMin();
+        doReturn(5D).when(region).getShoreHeightMax();
 
         IrisBiome resolved = IrisComplex.resolveSurfaceBiome(
                 68D,
@@ -143,6 +145,8 @@ public class IrisComplexSurfaceBiomeTest {
         IrisRegion region = mock(IrisRegion.class);
         doReturn(false).when(base).isShore();
         doReturn(3D).when(region).getShoreHeight(12D, 18D);
+        doReturn(1D).when(region).getShoreHeightMin();
+        doReturn(5D).when(region).getShoreHeightMax();
 
         IrisBiome resolved = IrisComplex.resolveSurfaceBiome(
                 63D,
@@ -168,6 +172,8 @@ public class IrisComplexSurfaceBiomeTest {
         doReturn(false).when(aquatic).isShore();
         doReturn(false).when(aquatic).isLand();
         doReturn(1D).when(region).getShoreHeight(4D, 7D);
+        doReturn(0.5D).when(region).getShoreHeightMin();
+        doReturn(1.5D).when(region).getShoreHeightMax();
 
         IrisBiome resolved = IrisComplex.resolveSurfaceBiome(
                 66D,
@@ -193,6 +199,8 @@ public class IrisComplexSurfaceBiomeTest {
         doReturn(false).when(base).isShore();
         doReturn(false).when(base).isLand();
         doReturn(3D).when(region).getShoreHeight(12D, 18D);
+        doReturn(1D).when(region).getShoreHeightMin();
+        doReturn(5D).when(region).getShoreHeightMax();
         doReturn(0D).when(region).getShoreMinimumWidth();
 
         IrisBiome resolved = IrisComplex.resolveSurfaceBiome(
@@ -218,6 +226,8 @@ public class IrisComplexSurfaceBiomeTest {
         IrisRegion region = mock(IrisRegion.class);
         doReturn(false).when(base).isShore();
         doReturn(3D).when(region).getShoreHeight(12D, 18D);
+        doReturn(1D).when(region).getShoreHeightMin();
+        doReturn(5D).when(region).getShoreHeightMax();
         doReturn(3D).when(region).getShoreMinimumWidth();
 
         IrisBiome resolved = IrisComplex.resolveSurfaceBiome(
@@ -244,6 +254,8 @@ public class IrisComplexSurfaceBiomeTest {
         doReturn(false).when(base).isShore();
         doReturn(false).when(base).isLand();
         doReturn(3D).when(region).getShoreHeight(12D, 18D);
+        doReturn(1D).when(region).getShoreHeightMin();
+        doReturn(5D).when(region).getShoreHeightMax();
         doReturn(3D).when(region).getShoreMinimumWidth();
 
         IrisBiome resolved = IrisComplex.resolveSurfaceBiome(
@@ -272,6 +284,8 @@ public class IrisComplexSurfaceBiomeTest {
         doReturn(false).when(base).isLand();
         doReturn(false).when(base).isAquatic();
         doReturn(3D).when(region).getShoreHeight(12D, 18D);
+        doReturn(1D).when(region).getShoreHeightMin();
+        doReturn(5D).when(region).getShoreHeightMax();
         doReturn(3D).when(region).getShoreMinimumWidth();
 
         assertSame(sea, IrisComplex.resolveSurfaceBiome(
@@ -304,6 +318,8 @@ public class IrisComplexSurfaceBiomeTest {
     public void shoreBandTopTradesHorizontalWidthForHeightOnSlopes() {
         IrisRegion region = mock(IrisRegion.class);
         doReturn(3D).when(region).getShoreHeight(12D, 18D);
+        doReturn(1D).when(region).getShoreHeightMin();
+        doReturn(5D).when(region).getShoreHeightMax();
         doReturn(3D).when(region).getShoreMinimumWidth();
 
         assertEquals(66D, IrisComplex.shoreBandTop(67D, region, 12D, 18D, 63D, constantSlope(0D)), 0D);

core/src/test/java/art/arcane/iris/generation/stage/IrisTerrainNormalActuatorColumnParityTest.java

@@ -175,7 +175,6 @@ public class IrisTerrainNormalActuatorColumnParityTest {
             when(complex.terrainColumn(eq(X), eq(Z), hydrology == null ? isNull() : any(HydrologyColumnSample.class)))
                     .thenReturn(terrainColumn);
             when(complex.naturalTerrainColumn(X, Z)).thenReturn(terrainColumn);
-            when(complex.resolveSurfaceFluid(anyDouble(), anyDouble())).thenReturn(fluid);
             when(context.getRoundedHeight(0, 0)).thenReturn(he);
             when(context.getBiome()).thenReturn(new ChunkedDataCache<>(
                     ProceduralStream.of((x, z) -> biome, Interpolated.of(value -> 0D, value -> biome)), X, Z, false));
@@ -183,6 +182,8 @@ public class IrisTerrainNormalActuatorColumnParityTest {
                     ProceduralStream.of((x, z) -> region, Interpolated.of(value -> 0D, value -> region)), X, Z, false));
             when(context.getRock()).thenReturn(new ChunkedDataCache<>(
                     ProceduralStream.of((x, z) -> rock, Interpolated.of(value -> 0D, value -> rock)), X, Z, false));
+            when(context.getFluid()).thenReturn(new ChunkedDataCache<>(
+                    ProceduralStream.of((x, z) -> fluid, Interpolated.of(value -> 0D, value -> fluid)), X, Z, false));
             when(biome.generateLayers(eq(dimension), anyDouble(), anyDouble(), any(RNG.class),
                     anyInt(), anyInt(), eq(data), eq(complex))).thenAnswer(invocation -> layers("layer", layerCount));
             when(biome.generateSeaLayers(anyDouble(), anyDouble(), any(RNG.class), anyInt(), eq(data)))

core/src/test/java/art/arcane/iris/generation/stage/IrisTerrainNormalActuatorHydrologyTest.java

@@ -259,6 +259,8 @@ public class IrisTerrainNormalActuatorHydrologyTest {
                     ProceduralStream.of((x, z) -> region, Interpolated.of(value -> 0D, value -> region)), 11, -4, false));
             when(context.getRock()).thenReturn(new ChunkedDataCache<>(
                     ProceduralStream.of((x, z) -> rock, Interpolated.of(value -> 0D, value -> rock)), 11, -4, false));
+            when(context.getFluid()).thenReturn(new ChunkedDataCache<>(
+                    ProceduralStream.of((x, z) -> null, Interpolated.of(value -> 0D, value -> null)), 11, -4, false));
             when(biome.generateLayers(eq(dimension), anyDouble(), anyDouble(), any(RNG.class),
                     anyInt(), anyInt(), eq(data), eq(complex))).thenReturn(new KList<>(List.of(grass)));
             Hunk<NativeBlockState> output = Hunk.newArrayHunk(1, 64, 1);

core/src/test/java/art/arcane/iris/generation/stage/IrisTerrainNormalActuatorStrataCutTest.java

@@ -155,6 +155,8 @@ public class IrisTerrainNormalActuatorStrataCutTest {
                     ProceduralStream.of((x, z) -> region, Interpolated.of(value -> 0D, value -> region)), 11, -4, false));
             when(context.getRock()).thenReturn(new ChunkedDataCache<>(
                     ProceduralStream.of((x, z) -> rock, Interpolated.of(value -> 0D, value -> rock)), 11, -4, false));
+            when(context.getFluid()).thenReturn(new ChunkedDataCache<>(
+                    ProceduralStream.of((x, z) -> null, Interpolated.of(value -> 0D, value -> null)), 11, -4, false));
             when(biome.generateLayers(eq(dimension), anyDouble(), anyDouble(), any(RNG.class),
                     anyInt(), anyInt(), eq(data), eq(complex))).thenReturn(new KList<>(List.of(grass, dirt)));
             when(biome.generateCeilingLayers(eq(dimension), anyDouble(), anyDouble(), any(RNG.class),